The exploration of offshore areas for oil and gas is performed almost exclusively with boats towing one or more of a variety of seismic sources and a large number of hydrophones near the surface of the water. Generally, the seismic sources towed behind the boat emit a sharp pulse which travels down through the water, through the seafloor, into the subseafloor region, and reflects off the interface between two geologic layers of differing densities. The reflected pulse then retraces a similar course and is detected by the hydrophones towed behind the seismic boat.
The hydrophones are typically included in a long streamer cable. The cable may be made up of a number of sections, each filled with oil for proper buoyance and containing a number of hydrophones. Modern cables may be two miles or more in length and contain 4,000 hydrophones. A long cable with a great number of hydrophones provides better resolution of the shape of subsurface geologic features than does a shorter streamer with a smaller number of geophones and often does so with less background noise.
As mentioned above, the cable may be made up of a large number of sections. In this way, if the cable is damaged, e.g., by shark bite, it can be pulled onto the boat until the damaged section is brought aboard, the section unplugged, a new section installed and the cable redeployed in the water. Repairs to the damaged cable may be undertaken without substantial interruption of the exploration activity.
One of the greatest sources of unreliability in a marine seismic cable lies with the electrical connectors used to join adjacent sections of cable. It is not uncommon that a cable will have ten fifty-pin connectors at each of its ends. These connectors are located in a boot which may be up to six feet in length. The connectors typically have small delicate pins and sockets which are subject to mismating. Mismating the two connector halves tends to bend or break the small pins. The large number of mating pins requires special tools to overcome the high friction resistance in separating the halves. The boots may be rigid, in contrast to the pliable nature of the section body, to protect the integrity of the sockets. The junction between the pliable cable sections and the rigid boots, therefore, is susceptible to separation or tearing. The cables and connectors described in U.S. Pat. No. 4,204,188 to Weichart et al, issued May 20, 1980, and U.S. Pat. No. 4,260,211 to Mollere, issued Apr. 7, 1981, are typical of this design. A similar device having a pivoted junction between cable sections is disclosed in U.S. Pat. No. 3,350,678 to McLord, issued Oct. 31, 1967.
As noted above, an aspect of the instant invention is the use of flexible magnetic substrate as part of a flexible electrical connector having near-flush contacts imbedded therein.
Other connectors using flush contacts are known. See U.S. Pat. No. 2,234,982 to Ross, issued Mar. 18, 1941 and U.S. Pat. No. 3,080,544 to Statt et al, issued Mar. 5, 1963. U.S. Pat. No. 3,731,258 to Spicer, issued May 1, 1973, discloses both flush contacts and a flexible rubber substrate. None of Ross, Stratt et al, or Spicer, however, disclose a flexible magnetic substrate.